This invention relates to a quick disconnect coupler having an improved seal which is axially fixed in place on the housing of the coupler, yet which effectively seals against all three of the commonly used coupler plugs.
Quick disconnect couplers are in widespread use for releasably joining pneumatic and fluid transfer lines. In general, quick disconnect couplers use hardened balls or pins which engage a groove in the coupler plug to hold it securely against a soft seal while permitting the assembly to swivel, thereby preventing kinking or twisting of hoses. A sliding sleeve is manually retracted to release the locking balls or pins, thereby permitting the plug to be inserted or removed. The sleeve automatically returns to the lock position when released. Generally, an automatic shut-off valve is provided in the coupler to seal the central passageway of the coupler automatically upon uncoupling. This eliminates the need for a separate shut-off.
In the past, a number of sealing approaches have been used to seal the housing of the coupler to the coupler plug. One approach is to use O-rings captured in place in the housing of the coupler, as shown for example in Karcher, et al., U.S. Pat. No. 4,833,951. A second approach is to use a cylindrical sealing surface that provides a radial seal, as shown for example in Gailey, U.S. Pat. No. 4,825,893. A third approach is to use a cut washer which abuts the extreme end surface of the coupler plug to provide the required seal. See, for example, the quick disconnect couplers shown on page 4 of the Amflo Coupler and Plug catalog. In the coupler shown in the Amflo catalog, the automatic shut-off valve is spring biased to seal against the opposed side of the cut washer.
At least in the United States, coupler plugs are not standardized. In fact, three types of coupler plugs are in common use, and they differ substantially in the outer diameter of the nose of the coupler plug, and in the axial position of the nose of the coupler plug with respect to the annular retaining groove of the plug. It would be advantageous to provide a quick disconnect coupler that seals reliably against all three commonly available coupler plugs.
A prior art approach to providing a quick disconnect coupler which is intended to seal all three commonly available plugs is to use a seal in the coupler which slides axially along the length of the coupler as necessary to seal against any one of the three plugs. The structure of this prior art coupler is similar to the Hansen AUTO-FLO 20 coupler shown in various catalogs of the Tuthill Corporation, Hansen Coupling Division. In this arrangement, the coupling plug shifts the seal axially along the central passageway of the housing as necessary to bring the seal into sealing engagement with the nose of the plug. The illustrated design has a cylindrical, inwardly facing sealing surface, and the sliding seal is spring biased towards the retaining elements by the automatic shut-off valve. Such sliding seals are relatively complex in structure, and they require a number of additional parts. For this reason, the three-way coupler described above is relatively complex mechanically as compared to conventional fixed seal couplers.
Accordingly, it is an object of this invention to provide a quick disconnect coupler that seals any one of the three commonly used coupler plugs without relying on seals that slide axially in the coupler housing.